Blindstitch sewing machine



(Pct. 27, 1931. A. STROBEL BLINDSTITCH SEWING MACHIX E Filed Aug. 20, 1928 3 Sheets-Sheet l a a a m m w [Ufa/15 57 r0be/ INVENTOR BY L ATTORNEY Oct. 27, 1931. A, STROBEL 1,828,789

BLINDSTITCH SEWING MACHINE Filed Aug. 20, 1928 3 Sheets-Sheet 2 I IN l NVENTOR BY A 4J4 ATTORNEY Get. 27, 1931 A. STROBEL BLINDSTITGH SEWING MACHINE Fil'ed Aug. 20, 1928 3 Sheets-Sheet 5 Patented Oct. 27, 1931 o ITED STAT-ES PATENT ALFONS STROBEL, F MUNICH, GERMANY BLINDSTITCH SEWING MAGHINE Application filed August 20, 1928, Serial No. 300,835, and in Germany November 21, 1927.

lhis invention relates to blind stitch sewing machines, such as are used for sewing textile fabrics, hides, skins and similar materials. s The invention has for its object to provide an improved machine by means of which work can impossible on such machines and which enables such work as hitherto done on such ma- 1o chines to be considerably facilitated, to be carried out more accurately and in much shorter time.

According to, the present invention, the feeder for the material to be sewn is mounted on a vertically oscillatable arm carried by a pivot sleeve mounted on the frame of the machine, said pivot sleeve having a finger which is acted on by a spring-controlled pressing member so as to urge the oscillatable arm upwardly into its highest position, and

a lever which extends upwardly from the pivot-sleeve and cooperates with an adjustable stop screw for limiting the upward movement of the arm, said lever having a springcontrolled pawl which cooperates with an abutment on the frame of the machine in such a manner that, when the oscillatable arm which carries the feeder is in its lowest position the pawl is adapted to retain the arm in this position.

By means of this arrangement, not only is space saved but the work is facilitated, since the member which carries the feeder (and preferably also the work bender) is not rigidly mounted on the frame of the machine and does not form a bulky projection. The arm on which the feeder is mounted is not wide, so that the material to be sewn can hang down freely on the right and left of it, 40 whereby it is possible to sew tubular work on the machine.

In order to enable two or more layers of material to be-sewn together in such a manner that they-will subsequently remain in the rolled up state, means comprising a saddle are preferably provided, said saddle being arranged below the stitch plate opposite a slot in the latter through which the material to be sewn is forced for enabling the needle to pass through the material, the arrangebe done which has hitherto been ment being such that the uppermost layer of material is sewn on a larger circumference than the other'layer or layers. Blind stitch'sewing machines as hitherto constructed produce exclusively blind m5 stitches. It is desirable, however, to carry out other work also, particularly sewing with some of the stitches passing right through to the back of the WOI'k,'-OI' instance when sewing the canvas on mens coats, overcoats or r the like, where stitches have to be visible on both sides of the material. A seam of this kind is called a blind stitch seam with through stitches. For this purpose, in the machine according to the invention, a work bender is provided by means of which the work can be pushed through the slot in the stitch plate to a greater or less extent, the arrangement being such that when the material is a short distance the needle will pass through the material tangentially without piercing it through to the other side while when the material is forced through a greater distance the needle will pierce the material right through, the length of the stitches increasing on the back of the material in proportion to the distance the material is forced through the slot. The work bender preferably comprises two discs, one of which serves for sewing the blind stitches while the other disc partly overlaps it and is adapted to raise the material by varying amounts according to the len th of the stitches to be visible at thebac beyond the amount by which the ma- I terial is raised by the first-mentioned disc. To prevent.the needle from becomingjammed, the second-mentioned disc is made smaller than the first-mentioned disc so that a'step is formed by the overlapping discs in the gap of which the needle can oscillate to r and fro without fouling the work bender. An embodiment of the invention is illustrated in the accompanying drawings, in

which Figure 1 is a side elevation, partly in section, of the sewing machine; Figure 2 is a top plan view thereof;.Figure,3 is a cross sectlon on the line 3-.-3 of Figure 2; Figure 4 is an end elevation, showing the oscillatory arm; Figure 5 is a cross section on the line forced through the stitch plate only 70' 5-5 of Figure 6 of means for sewing rolled layers of cloth; Figure 6 is a side elevation of the mechanism shown in Figure 5; Figure 7 is a cross section on the line 77 of Figure 6; Figure 8 shows two layers of cloth sewn together by the present machine; and Figure 9is a detail view of the work bender;

In the arm 1 of the frame a driving shaft 2 is mounted which is rotated from the driving pulley 3. The driving shaft 2 transmits its rotating movement to the needle 32 through an eccentric and connecting rod not shown in detail. From the main shaft 2 a secondary shaft 5 is rotated through the intermediary of a transmission gear 4. The secondary shaft5 is journaled in a pivot sleeve 7, oscillatably mounted in the foot part 6 of the frame and carrying rigid with it anoscillatory arm 8 extending perpendicularly to the pivot sleeve. The oscillatory arm 8 is hollow and in the same is located a connecting rod 10 driven by an eccentric 9 keyed on the secondary shaft 5. The free end of the oscillatory arm is provided with a work bending mechanism more fully hereinafter described. From the pivot sleeve 7 projects a finger 11 against which bears a depressing member 12 controlled by a spring 13 and arranged to press the oscillatory arm 8 vupwardly. The material to be sewn is held between the stitch plate 31, which is fixed, and the work bending mechanism on the free end of the arm 8, which is rocked downwardly against the action of the spring 13 to enable the material to be sewn to be inserted between the stitch plate and the work benders. The force of spring 13 may be adjusted by an adjusting screw 14. On the pivot sleeve 7 is also fixed a clamping lever 15 which carries a pawl 18 controlled by a spring 16 and pivoted on pin 17. The movement of the lever 15 in counter-clockwise direction and thereby the upward movement of the oscillatory arm is limited by an abutment screw 19. An adjusting member 20 which engages the upper end of lever 15 and which is adapted to be adjusted by a nut 21, serves for limiting the upward movement of the arm 8 at different points intermediate of the extreme limit set by screw 19. To enable theoscillatory arm to be brought into the inoperative position when required and retained in that position it is depressed until the pawl 18 can engage the catch 22. By this means access can be had to the work bending mechanism.

On the under side of the stitch plate 31 (Figures 5 to 7) two bosses 68 are arranged which together form a semicircular cavity. In the lower part of the machine a lever 69 is mounted so that it can oscillate around a pivot pin 70 carried at the free end of the oscillatory arm 8. This lever 69 is controlled by a spring 71 attached to the lower arm of the lever, while the. end 72 of the other arm of lever 69 carries a "plate 73 having a curved portion of semicircular cross section, hereinafter termed the saddle, fitting into the semicircular cavity or hollow between the bosses 68 of the stitch plate 31. The saddle 7 3 has an aperture 74 into which the work benders 24 and 26 can swing, in order to enable the needle 32 to sew through the cloth as well as produce blind stitches. The cloth is fed from above by a cloth feeder 75 which engages into the slot between the bosses 68 in the stitch plate 31 to feed the cloth.

It is evident that of two or more layers of cloth placed over the saddle 73, the uppermost layer must be curved to a greater radius but at the same angle as the other layer or layers. If the material is sewn in this position with several seams, the upper cloth layer will be curved upward, when the material is being stretched, so that hollow spaces 76 (Fig. 8) are formed which resist the tendency of the cloth to adopt the stretched position so that rolling or curling of the cloth is produced. It is immaterial whether the cloth is tacked with an ordinary throughstitch seam or with a blind-stitch-seam. The use of a blind-stitch seam, specially desirable for flats, batts, reverses and the like, increases materially the rolling effect by its peculiar position as it exerts an elastic action, the stitch traversing the cloth in a semicircle. Owing to the fact that the saddle 73 bears continually and resiliently against the bosses 68 of the stitch plate 31, the cloth is pressed positively into the semicircular position and every consecutive seam resembles the preceding one, this being notthe case when sewing by hand as this work has to be carried out according to touch. Consequently the work done with the aid of the device according to the present invention is much more accurate than it could be done heretofore-by hand or by machine. 4

The vibrating movement of the connecting rod 10 imparted to the same-by the rotating eccentric 9 is transmittedzto a work bender shaft 23, on which the disc 24 is mounted designed for blind stitching. On the shaft 23 a sleeve 25 is mounted from which projects the second larger disc 26 the upper edge 27 if which overlaps the disc 24. The sleeve 25 with the disc 26 is adjustable so that it can be rocked into a lowered position in which it does not enter into full eflect and from that position into a second position in which it partly overlaps the disc 24 so that it exerts its complete action. The two extreme positions of sleeve 25 can be determined by an adjusting mechanism (not shown). The second disc 26 is secured in its different positionby different notches.

The operation of the work bending mechanism is as follows If the cloth 29 is merely to be blindstitched, the disc 24 having the smaller radius is used for lifting the cloth into the slot 30 of the stitch plate 31, so that the needle 32 cannot pierce through the cloth but merely passes tangentially therethrough, the stitch not being visible on the back. If the cloth is to be completely stitched through, the sleeve 25 is turned. In this position the second disc 26 having the greater radius covers almost completely the disc 24 and leaves uncovered only a small portion of the latter disc. The edge of the disc 26 projecting over the disc 24 lifts the cloth much higher into the slot 30 of the stitch plate 31, so that the needle 32 passes completely through the cloth 29. During the rearward movement of disc 26 the needle 32 cannot be clamped as, owing to the disc 24 being partly covered by the disc 26, a step open towards the machine is produced between said two discs through which the needle can freely move, even, if the discs 24 and 26 are oscillating rearwardly.

I claim 1. A blind stitch sewing machine, comprising in combination with a frame, an arm oscillatable on said frame, a pivot sleeve for said oscillatory arm, a finger extending from said pivot sleeve, a spring-controlled pressing element acting upon said finger, a lever upwardly extending from said pivot sleeve, a stop screw for limiting the backward oscillation of said lever, a pawl hingedly mounted on said lever, a spring controlling said pawl, and an abutment behind which said pawl hooks when said oscillatory arm is in its lowest position.

2. In a blind stitch sewing machine comprising a frame and a vertically oscillatable work supporting arm carried thereby, the combination of a transversely curved work support at the free end of saidarm, said work support having an opening approximately centrally thereof, and a plurality of means also at the free end of said arm and adapted to project the work varying distances above the opening in said support.

3. In a blind stitch sewing machine comprising a frame and a vertically oscillatable work supporting arm carried thereby, the

combination of a transversely curved work support at the free end of the arm, said support having an opening in the bridge thereof, and a plurality of different sized discs at the free end of the arm adapted to-project the work varying distances above the opening in said support.

4. In a blind stitch sewing machine comprising a frame and a vertically oscillatable work supporting arm carried thereby, the combination of a transversely curved work support at the free end of the arm, said support having an opening in the bridge thereof, a pivotally mounted work bending disc carried at the free end of said arm and a second work bending disc also carried at the free end of said arm, said second disc being larger than and but partly overlapping the first disc whereby a step for the free passage of a needle is formed between said discs.

5. In a blind stitch sewing machine comprising a frame having an apertured stitch plate, and a vertically oscillatable work supporting arm carried by the frame, the combination of a pair of bosses on the under side of the stitch plate at opposite sides of the.

hand.

ALFONS STROB-EL. 

